<!DOCTYPE html>
<html lang="en">
  <head>
    <meta charset="UTF-8" />
    <meta http-equiv="X-UA-Compatible" content="IE=edge" />
    <meta name="viewport" content="width=device-width, initial-scale=1.0" />
    <title>Document</title>
  </head>
  <body>
    <script>
      //实参可以是变量
      let sum1 = +prompt('请输入第一个数')
      let sum2 = +prompt('请输入第二个数')
      function getSum(a = 0, b = 0) {
        return a + b
      }
      console.log(getSum(sum1, sum2))
    </script>
  </body>
</html>
